Created back in the 1940s and put into widespread commercial use in the 1970s, the humble bar code revolutionized everything from shopping to inventory management. Ever since then industrious researchers have been refining and reinventing optical machine-readable tags.

Among all the various revisions and brand new tag methods, Quick Read (QR) codes have enjoyed the most widespread adoption. The format was invented by Toyota subsidiary Denso Wave in 1994 to assist in tracking vehicles and materials in their production facilities and has since spread to everything from shipment labels to magazine ads.

Two primary factors contributed to the rise of the QR code. Unlike other bar code alternatives like the Aztrec Code or High Capacity Color Barcodes, the QR code format is essentially open–the specs are shared freely and patents on the format are purposely not enforced to encourage proliferation of the format. In addition, the radical increase in smartphone ownership over the last decade has effectively put a code scanner in everyone’s pocket–it’s extremely easy for consumers to whip out their phone, scan a QR code (be it on a magazine page or a billboard) and immediately access web sites, apps, and other material.